Production of a road joint sealing composition



Patented Mar. 5, 1946 was ii I PRODUCTION orsnoanrom'r same 1 tCOMPOSITION 1 John '1'. 'Doyle, deceased, late of Anne Arumilel County,Md.; by Mary Doyle, administratrix,

j Baltimore, Md.

No Drawing. Application May 1942, a "Serial No. 444,935

icamw -The invention relates to the construction of" concrete andsimilar pavements which in order. to prevent ,or reduce cracking dueto'expansion and contraction with changes-oftemperature are castinisections which-are spaced incorrespond- Y ence with the degreeofcontraction and expansion' expected. These spaces or;joints between thesections are bridged at a level below the road surface by load transfermembers cast in the concrete and are usualiyfllled below the surface l0with a precast asphaltic or other resilient filler which :is placed inposition before pouring the V concrete. The joints'mayextendlongitudinally of the roadway as well as transversely,

An extremely important consideration is theeir- .15,

clusion of moisture the entrance of which into the joints and throughthe joints into the subgrade causes disruption due to alternate freezingand thawing, hencethe necessity for 'p the moisture proof seal, which isthe subject oftheinvention.

In the process of construction the precast filler plates or such fillerasmay. be empioyed are set on the iinesiof the joints, each inuprightposition, with itstopedge below-the road. surface.

This leaves. a rabbet or groove which in cross sec- .ticn is customarilyabout. three quarters of flan inch b three quarters of aninchorthereabouts; overlying the filler-at the top oi-the joint. This a b tgroove or r b at is subject to can motion and 39 of these Joint sealingcomposition's also lack the expansion transversely of its'iength as the.concrete sections or slabs between which it islocated expand andcontract. When the pavement is set these grooves :or

rabbets arefliied with a-sealing compound the 3x5 mainpurpos'e of whichis to prevent the entrance or moisture into the joints and through thejoints intothe subgrade. A" purpose is also of importance istoiill thejoints substantially flush with the roadlsurface and thusbridgetheiointsto preventing the-bumping of the tires in passing he on er e cee it to im h I. The problempresented is diiierent i'rom that involved in thesealing of road cracks, and the compositionssuitable for the latterpurpose are not suitable 1'0! use inthejsealin ofthefjoints and likewisethe present composit n in the, prei'erred Iorm s ibt'sui e to t e se lig" 1 f l d cracks as iii-sets or partiailyfsets sopromptly that itvcannot be satisfactorilyintroduced into openings 0! the width which suchcracks normally In the mid-temperate zonc to which the bulk oithe areaof the United States proper may ation. of F. being close to the average;

A satisfactory road sealing compound must be capable of low costproduction, and easy of ap-' plication and should meet thesetemperaturecon ditions and continue over a long period to be e'f v fectiveinthejexclusion ofwater and in the bridging of. thegroovein suchainanner as 'to substantially eliminate bumping of the tires in crossing the joints. Various bituminous compounds and mixtures of rubber,asphalt, tar and other piastiosubstances have been employed ,withnotable absence of satisfactory. results. So far as can be ascertainednosatisfactory composition for this purpose. which can be produced at afigure commensurate with a reasonablecost of construction has yet beenproduced or offered to the builders of, concrete and similar pavements.

i The difliculties encountered include primarily the tendency of thesealingcornpo sition to harden and crack in cold weather when theconcrete sections or slabs contract andgthe grooves or rabbetsexpandfand these cracks form leaks which admit water tofthe'ioints andto the 'subgrade. Afurther difliculty is the tendency of the sealingmaterial to liquefy at the higher road temperatures so that it escapesfrom the Joints bothby' leakage andby distribution over theroad. surfacedue to partial adhesion to vehicletires. .The majority escape from thejoint by leakage and adhesion.

to the tires of passing vehicles. There is' also a tendency of the priorcompositions due to alternate heating and cooiing't'o form hardprotuberances which i cause highly objectionable bumping of the tires. 6Y c .The object of the present invention isthe production and applcation .of a concrete road joint sealing composition whereby .thedifliculties above recited and other diflicultieswhich occur .in'the.manufacture and use oithe previously known compositions for this purposeare overcome;

said to bciongg'there is an an iuai variatioiijcr c i Th compositionhasbeen thoroughlytested prevent escape from the joint and to prevent lossto meet the conditions encountered having been mentioned.

In the practice of the process whereby the desired result has beenattained the materials in suitable proportion, for example 70 partsasphalt to 30 parts oil thus mixed are blown with air to a softeningpoint designated as approximately 135 F., a reasonable degree ofvariation above and below this point being regarded as feasible bysmearing on the pavement surface and on the tires of passing vehicles.It is also of importance that this composition affords satisfactorysupport;

for the tires in passing the joints and does not form protuberanceswhich would cause bumping of the tires, nor does it when properlyapplied.v become separated from the sides or side walls.

of the grooves, particularly in cold weather, forming cracks which admitwater. It also has satisfactory sealing properties at medium,temperatures. V j

In the practice of the invention. in' what is regarded as the preferredform, a reasonable degree of variation and substitution beingcontemplated, the disclosure serving mainly as an example .of. thesuccessful practice of the invention, the sealing composition ismanufactured by blending a material having the properties andcomposition of steam refined asphalt made from Texas crude orsubstantially such properties, the same being of approximately 50-60penetration by the standard penetration test which is understood to mean50 to 60 one hundredths of a centimeter penetration by a standard testneedle under 100 grams pressure applied for a period of five seconds ata temperature of 77 F. A blend which has been successful in the practiceof the invention comprises 70% asphalt of the quality above describedand by volume of an intermediate or flux oil.

The above description is intended to define an asphaltof high ductilequalities containing little or no paraffin and the minimum of sulphur,both 0% which constituents are regarded as undesira le.

Steam refining is mentioned as giving thedesired result, the possibilityof obtaining similar conditions and results and an asphalt of similarqualities by other. methods of refining being recognized, the method ofproducingthis constituent not being a feature of the invention.

The proportions stated and the quality of the thinning or intermediateoil are also subject to such variation as does not forfeit the essentialproperties of the resulting composition. The intermediate or flux oilused is preferably free or substantially free of sulphur and paraffin.

An intermediate or flux oil which has proved satisfactory for thispurpose may beidentified as follows according to generally recognizedstandard tests.

Anfgriniszn Petroleum Institute hydrometer 60,

Flash point, C. O. 0. (Cleveland open cup), 480 F.

Furol viscosity, 210 F. 45 seconds.

Float test, 150 F. l6-seconds.

and a variation from 130' F. to 140 F. having been ascertained as notinterfering with the usefulresult attained. The temperature of thesoftening point or melting point of the blend is raised by blowingasdescr'ibed, and the ductility at high temperatures is reduced. Mixingas described gives anincreased ductility and penetration at .lowtemperature which is retained to a satisfacoil which is found to.besatisfactory for this purpose, the possibility of variation andsubstitution tory degree after blowing. The properties of the combined,materials are thus determined by mixing and blowing, the result being asatisfactory joint sealing-compound. The term softening point thusemployedhas reference to a standard test prescribed by the AmericanSociety for the Testing of Materials and'thus identified. Blowing-isunderstood to effect partial oxidation. A blowing temperature of 485F.;has been found satisfactory. Compensating variations of time, airsupply and temperature may be practiced.

The resulting material when used as a concrete road jointsealingcompound conforms to the requirements above recited. This compositionmay be characterized and identified according to the practiceinselecting'and determining petroleum and similar plastics as follows:

Melting point (ring and ball test), approximately 135 F. v

Penetration by standard test 32 F., 200 grams pressure standard testneedle duration 60 seconds, minimum 20, approximately normal variation20 to 30 (unit of penetration being ,6 centimeter) d f Penetration, 77F.. 100 grams pressure standard test needle} duration 5 seconds,approximately 50 'to' 60 units of penetration.

Penetration, 115 F., 50' grams pressure, 5 seconds maximum,approximately 1'75 units of penetration by standard test needle. Y

' Ductility 7'1 F; stretching at rate of 5 centimeters'perminute,"approxiinate stretch 80 to without cracking;

Ductility, 32 F. stretch at rate of 0.25 centimeter per minute withoutcracking approximately 4.

Flash point, approximately 500 F. The ductilities referred to aredetermined by and stated in terms of test B 113-39, American Society forTesting Materials.

Solubility in carbon disulphide, 99% minimum. The foregoingspecification identifies the prodnot of the invention in the preferredform from which some relaxation of the requirements or a degree ofvariation may be permitted. The asphaltic composition of the inventionis regarded as unique in the attainment of this standard particularly as.to excessive ductility and penetration at low temperatures and arelatively low maximum penetration at high temperatures as stated, whichconstitute a notable accomplishment in a composition for the sealing ofjoints of. concrete pavements. The other properties stated are givenmainly for the purpose of describing the composition in what is atpresent regarded as the preferred form. j

In sealing the joints of concrete roads in accordance with the preferredpractice of the invention the sides or side walls of the groove orrabbet at the top of the joint are preferably first coated with anasphaltic paint following which the grooves or rabbets are filled withthe joint sealing composition of the invention, for which purpose thesealing composition is liquefied by heating, the temperature beingpreferably from 325 to 340 F., 350 being regarded as the maximumtemperature to which it can be heated Without probability ofdeterioration. Other priming fluids may be employed.

This sealing composition is of an asphaltio nature having the propertiesabove identified and imparted to it by the treatment, above defined.

A satisfactory material for priming or coating the walls of the groovesor rabbets to improve the adhesion of the composition may be made bycombining a liquid petroleum product substantially of the nature ofnaphtha or the equivalent or other suitable thinning agent with a 50-60steam refined asphalt or asphaltic composition of the propertiespreviously defined under this heading, the manner and source ofproduction being immaterial.

This mixture or paint may consist of 70% naphtha or the equivalent to30% asphalt which is preferably of the quality used in the sealingcomposition the proportions and constituents being subject to somevariation. Other tion being specific and in detail in order that themanner of practicing, applying and using the invention may be fullyunderstood. However, the

composition and the method described are subject to variation in thelight of a full knowledge of the nature of the materials and problemsinvolved and the specific terms are used in a descriptive rather than alimiting sense, the scope of the invention being defined in the claim.

What is claimed as new and desired to be secured by Letters Patent'is:

The method of making a sealing composition for concrete road joints,which consists of blending approximately 70% asphalt, the same having apenetration of -60 at 77 F., the said asphalt being combined with 30% byvolume of an intermediate oil containing practically no parafiln, and.

practically no sulphur, the said oil having a flash point ofapproximately, 480 F., a Furol viscosity of approximately, 45 seconds at210 F., and a float test at 150 F. of approximately 16 seconds,

thereafter blowing with air at a temperature of approximately 485 F. fora period suflicient such that the resulting material will have asoftening point by the ring and ball test of approximately, 135 F.penetration at 32 F., approximately, 20 to 30, under a thrust of 200grams for seconds, penetration at 77 F., approximately 50-60, under athrust of grams for 5 seconds, and a penetration at F., of approximately175, under a thrust of 50 grams for 5 seconds, a ductility at 77 F., ofapproximately 80 to 100, a ductility at 32 F., approximately 4, andflash point of approximately 500 F.

' MARY H. DOYLE, Administratria: of the Estate of John T. Doyle,

Deceased.

